Surfactant-modified nickel zinc iron oxide/polymer nanocomposites for radio frequency applications

Author： Yang Ta-I. Brown Rene Kempel Leo Kofinas Peter

ISSN： 1388-0764

Source： Journal of Nanoparticle Research, Vol.12, Iss.8, 2010-10, pp. : 2967-2978

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Abstract

Low loss, flexible, polymer nanocomposites with improved magneto-dielectric properties at radio frequencies (RF) were successfully fabricated. Surfactant-modified nickel zinc iron oxide (NiZnFe₂O₄) nanoparticles with ferrimagnetic behavior at room temperature were synthesized by a seed-mediated growth method. The surfactant prevented NiZnFe₂O₄ particle aggregation and provided compatibility with [styrene-b-ethylene/butylene-b-styrene] block copolymer matrices. NiZnFe₂O₄/polymer composites were prepared by a solution-casting method. Experimental results showed that the dielectric permittivity (ɛ_r) and magnetic permeability (μ_r) of the polymer composite increased with increasing amount of NiZnFe₂O₄ doping. The dielectric loss (tanδ) was less than 0.010 at 1 GHz frequency. The increased miniaturization factor ((ɛ_rμ_r)^1/2) and relative wave impedance ((μ_r/ɛ_r)^1/2) of the NiZnFe₂O₄ nanocomposites could potentially lead to a reduced RF device’s physical size with ease in impedance matching. Dynamic mechanical analysis (DMA) revealed that nanocomposites maintained 125% strain (elongation at break) with 30% nanoparticle doping.